Method and apparatus for constructing subterranean concrete walls



July 7, 1964 G. MIOTTI 3,139,729

METHOD AND APPARAT F0 ONSTRUCTING SUBTERRANEAN CR WALLS Filed Jan. 8, 1960 6 Sheets-Sheet l 2 I mun-mil Inventor GMSU M B u an, anus,

I) 6! $85,: Attorneys July 7. 1964 Filed Jan. 8, 1960 G. MIOTTI METHOD AND APPARATUS FOR CONSTRUCTING SUBTERRANEAN CONCRETE WALLS 6 Sheets-Sheet 2 Inventor MICTT/ /csue y 7, 1954 G. MIOTTI 3,139,729

METHOD AND APPARATUS FOR CONSTRUCTING SUBTERRANEAN CONCRETE WALLS Filed Jan. 8, 1960 6 Sheets-Sheet 3 FLA 22 c? Do 0 0| If O nuenlor "7/0305 M10777 July 7, 1964 MlQTTl 3,139,729

METHOD AND APPARATUS FOR CONSTRUCTING SUBTERRANEAN CONCRETE WALLS Filed Jan. 8, 1960 6 Sheets-Sheet 4 i I Fig I l 15 Q 4 HL i 13 1 13 E T 14 I 16 r F? 8 4 i I 47 17 17 r iVTl-JS 1/ 27 7 1x {a I 22 2a 22 28 21 July 7, 1964 Q MIOTTI 3,139,729

METHOD AND APPARATUS FOR CONSTRUCTING SUBTERRANEAN CONCRETE WALLS Filed Jan. 8, 1960 6 Sheets-Sheet 5 Bang ff .1,, =9 2% m 1 K Inventor G105 U6 Mic-7'77 Attorneys July 7, 1964 MIOTTI 3,139,729

G. METHOD AND APPARATUS FOR CONSTRUCTING SUBTERRANEAN CONCRETE WALLS Filed Jan. 8, 1960 6 Sheets-Sheet 6 Inventor 05 u? Mm rr/ B H500 BRawn/e; saw-q be k v AEUPm-DGF Attorney 5 United States Patent METHOD AND APPARATUS FOR CONSTRUCTING SUBTERRANEAN CONCRETE WALLS Giosue Miotti, Milan, Italy, assignor to Messr I.C.O.S. gmpresa Costruzioni Opere Speciaiizzate S.p.A., Milan,

Filed Jan. 8, 1960, Ser. No. 1,198 Claims priority, appiication Italy Jan. 10, 1959 Claims. (Cl. 61-46) There is known from earlier patents a method devised by Prof. C. Veder for the formation in sub-soil of impermeable partition walls constituted by a series of vertical concrete elements cast in individual consecutive excavations made in such a way that each excavation intersects the cross section of the adjacent, previously formed vertical element.

To carry out this method there is preferably used a flat hollow chisel through which is introduced into the excavation a substance, for example bentonite, which fills the excavation and makes the walls of the excavation impermeable and which, if caused to circulate at the same time brings to the surface the excavated material.

According to the first embodiment, the excavations, and therefore also the vertical concrete elements, which intersect one another, are of circular cross section; but in order to accelerate operations and to reduce the number of joints, it is preferred, whenever possible, for the excavations and thus also the concrete elements to have an elongated cross-section which can be obtained, for example, by the gradual displacement of the flat, hollow chisel during its work along the line of the partition walls its vertical percussion movement being combined with a slow translatory movement. According to a second embodiment, the material comprised between two circular excavations spaced apart from one another by a distance greater than their diameter, is removed by means of devices other than the chisel (for example, grab buckets or the like).

The first embodiment does not lend itself, however,

to being applied in the case, met with fairly often in practice, where the partition walls must follow a curved track, while the second embodiment, in addition to its inapplicability in rocky or heterogeneous terrain, does not permit the filling of excavations of circular cross-section prior to excavating the earth situated therebetween, for the very reason that it is based on the employment of tools unsuitable for treating concrete.

The method according to the present invention is derived partly from the said second embodiment and partly from the first embodiment. It renders the second em bodiment applicable also in rocky or heterogeneous terrain and permits excavations having circular cross-section to be filled with concrete prior to the excavation of the intermediate earth; with regard to the first embodiment it also offers the advantage of reducing the number of excavations for a given length of partition walls and of reducing to the minimum the removal of the material of the elements already cast, while it increases to the utmost the bonding surface with the interposed element and imparts to the latter a square cross-section which facilitates the inclusion in it of iron reinforcements possibly to be incorporated.

The method according to the invention is characterised in that, after vertical concrete elements of cylindrical shape have already been cast in the sub-soil along a predetermined line of whatever shape and spaced apart from one another at any desired distance, there is effected by means of a chisel an excavation in the interval between two successive cylindrical elements while in the excavation there is introduced in known manner an impermeabilization thixotropic fluid such as bentonite or a like substance, ascraping operation being at the'same time undertaken on the mutually facing vertical surfaces of the two elements bordering the excavation by means of auxiliary blades of said chisel substantially shaped to conform with the convex shape of said surfaces and capable also of exercising a loosening action on the earth. (As used herein, the word earth makes reference to the material removed from the sub-soil, which may be of many different types, hard or loose, sandy or rocky, etc.) In this way there is obtained, by means of the loosening action and also the driving action of the 'thixotropic fluid introduced in the excavation, a complete removal of earth and the formation of a substantially rectangular excavation in which the subsequent casting of concrete builds up a section constituting a perfect link between the two adjacent cylindrical elements.

The apparatus for carrying out the above-indicated method comprises an excavating tool in which are combined with a central chisel, equipped with. feed channels for the bentonite or other suitable impermeabilization substance, lateral half-moon-shaped blades the convex surface of which faces the central chisel :and both their lower and upper edges being cutting edges, the blades being arranged in such way that during the percussion movement of the tool they scrape the two cylindrical concrete elements which border the intervening space in which the tool is made to operate, and that they enlarge at the same time and by their own action, the excavation produced by the central chisel. The particular suitability of the excavating tool for carrying into practical effect the method according to the invention, does not in fact exclude its useful application also to other work, for example making links between concrete work in general such as continuous caissons, dam blocks and like constructions.

The device is actuated, as mentioned above, by percussion in the same way as the ordinary chisel in that it is raised by an actuating member and drops by gravity.

In it the half-moon blades may be fixed or movable, i.e. capable of being moved apart from, or closer to, one

another.

This possibility of adjusting their distance may prove useful for the purpose of setting the fixed distance between the blades to that between the previously cast cylindrical concrete elements on which they have to Work, and also for the purpose of varying the distance of the blades during operation, for example whenever the previously cast elements exhibit deformations such as humps, owing to irregularity of the terrain and consequently of the excavation or for any other reason.

The afOre-mentioned possibility of adjustment is imparted to the half-moon blades by a piston displaceable by means of fluid pressure in a cylinder arranged in a head of the tool above the central chisel, each of the blades being linked with an extension of the piston by means of a pair of connecting rods, parallel with one another, whichare hinged to the blades and to the extension element of the piston, while another pair of parallel connecting rods links each of the blades with the cylinder body in such a way as to form with the first of the said pairs a hinged parallelogram the length of one side of which is adjustable, the distance between the blades and the central chisel being varied when the said one side is varied.

The cylinder is divided by the .piston into two chambers and according to the way the fluid, for example oil, is admitted to one of these chambers, discharging from the other, the scraper blades either move apart from, or approach, one another.

For the distribution of the fluid in the cylinder there may be provided an operating unit with control means which thus, in the case of an excavator with movable scraper blades, also forms part, together with said excavator, of the apparatus for carrying into eifect the abovedescribed method of excavation.

This unit comprises, in addition to a powered pump and a distributor with an associated operating lever, two pressure gauges respectively connected with the two cylinder chambers actuating the scraper blades, and a second cylinder, identical to the first actuating cylinder, the

chamber of which communicates on the one hand with the chamber of the first cylinder and on the other hand with the distributor. The piston of the second cylinder in the operating and control unit is provided on the outside with an index cooperating with a scale devised in such a manner that the displaceable index can indicate on it the mutual distance between the scraper blades of the excavator tool.

Embodiments of the invention are illustrated in the accompanying drawings in which there is shown in FIGS. 1, 2 and 3 respectively, an excavator tool with fixed scraper blades, in partial vertical section on the line II in FIG. 2, in a horizontal section on the line IIH in FIG. 1, and in sideelevation;

FIGS. 4 and respectively, in a perspective front elevation on different planes and in a plan view relating to the central portion, an excavator tool with fixed scraper blades in operation and, on either side of the drawing two different phases of execution of the linking sections between previously cast concrete elements;

FIGS. 6 and 7 a front elevation and transverse sec tion of an excavator tool with adjustable scraper blades, in which the blades are in the near or closed position;

FIGS. 8, 9 and respectively, a vertical section of an excavator tool with adjustable scraper blades, showing in the right half of the drawing the blades in the closed position and in the left half the blades in the open position, a section on the broken line IXIX of FIG. 8, and a side elevation;

FIGS. 11 and 12 respectively, the excavator tool with adjustable blades in operation in a perspective front elevation on different planes, and the outline in plan view of the link between the cylindrical elements obtained by means of concrete casting;

FIG. 13 an operating and control unit for the excavator tool with adjustable blades.

With reference to the embodiment of FIGS. 1 to 3, the tool 1 shown here has in a central position a chisel 2 projecting downwardly beyond a flat element 2 on both sides of which are situated ducts 3 which bring the bentonite into the excavation made by the tool 1. The ducts 3 branch off an upper central channel 4 and terminate somewhat above the lower end of the cutting edge of the chisel itself. Arranged on both sides of the chisel 2 are the half-moon-shaped scraper blades 5 which in this embodiment are fixed and are attached to and supported by lateral plates 6 with cutting edge 6' and by the transverse intermediate pieces 7 with cutting edge 7'.

Thus, in an excavating tool as shown by FIGS. 1 to 3, the distance between the scraper blades 5 must be adapted to the distance between previously cast cylindrical elements if the tool is to be used for an excavation comprising the complete interval between said elements. Preferably, however, such a complete excavation in a case where very compact earth has to be perforated is not carried out with a tool of fixed width. Being much more robust than the tool of adjustable width it is used to make an excavation of a cross section similar to the final section, but somewhat smaller, leaving it to the adjustable tool to complete the excavation and to scrape the elements which border it laterally. The way in which this excavation of somewhat reduced crosssection is made by means of the fixed tool shown in FIGS. 1 to 3 is illustrated in the central part of FIGS. 4 and 5 in which it is clearly shown that the half-moon blades 5 do not reach the previously cast element 8; but

A a the same drawings show on the left a concrete linking section 9, reinforced with irons 10, which was carried out after the widening of the excavation between two elements 8 by means of the adjustable tool which will now be described.

in the adjustable tool (FIGS. 6 to 9) is arranged, cen trally of the tool 1, a chisel 2 on both sides of which are situated bentonite ducts; these ducts, in the example of FIGS. 6 and 7, are constituted by two upper connections 11 branching oif an upper central channel 4, and by two lower connections 11' having direct outlets in opposite directions, and by two connecting pipes 12 which unite the connections 11 with the connections 11'.

in a centrally located upper head, somewhat above the chisel 2, an oil-fed cylinder 13 is provided in which moves a piston 14 which divides it into two chambers 15 and 16 (FIG. 8). On the outside the piston 14 is linked by means of a pivotally connected joint 17 with two plates 13 arranged side-by-side which constitute an extension thereof. Between these adjacent plates are pivotally connected at 19, 19 a pair of parallel connecting rods 21 and at 2:9, 2t? a symmetrical pair of connecting rods 22, which rods are pivotally connected at their opposite ends at 2 3, 23 and 24, 24 to the hali-moon-shaped scraper blades, 25 and 26 respectively. Th se scraper blades, which are provided with both upper and lower cutting edges, are also pivotally connected to a part or" the tool which is integral with the cylinder, each by means of a ditferent pair of connecting rods, 2'7 and 28 respectively. Thus, the blade 25 with the connecting rods 21 and 27 on the one hand, and the blade on with the connecting rods 22 and 25 on the other hand each form with the aggregate constituted by cylinder 13, piston 14 and plates 18 a deformable parallelogram of which one side, constituted by the said aggregate, may vary" in length by the displacement of the piston 14 in the cylinder 13, thus causing the position of the other sides, and therefore of the blades 25 and 26, to vary. The arrangement is such that there is achieved, with the aid of the said device and owing to the action of the piston 14, a mutual spacing apart or approach of the scraper blades 25 and 26, parallel to each other, according to whether the piston is displaced in the cylinder 13 in a downward or upward direction.

In FIG. 11 the excavationtool with adjustable scraper blades is shown in operation between cylindrical concrete elements 29 which have humps. According to whether the tool is located between projecting or reentrant parts of the concrete elements the scraper blades move either closer together or further apart in such a way that the opposite surfaces of the concrete elements 29 are scraped to perfection and a linking section may then be cast in concrete, as the section 30 with iron reinforcements 30a shown in the same FIG. 11.

For the displacement of the piston 14 in one or the other sense, according to whether the scraper blades are to be moved further apart or closer together, is provided a distributor unit 31 for the fluid (oil) from which two ducts 32 and 33 branch off which respectively communicate with chambers 15 and 16 of the cylinder 13. At least one section of each of these ducts is flexible and protected by a sheath 34 which allows them to be wound on a drum 35 and thus to follow the vertical displacements of the tool 1. The distributor unit 31 (FIG. 13) with operating lever 36 is also combined with a pump 37 driven by an electric motor 38, and with a reservoir 39, in order to force the oil under pressure from the reservoir 39 into one of the two chambers of the cylinders 13, the other chamber discharging into the reservoir 39, and vice versa. For checking the mutual distance of the scraper blades 25 and 26 there is provided a cylinder 40, equal to the cylinder 13 but included in the duct 33, the piston 40 of which is provided externally with an index 41 displaceable on a scale 42 the graduation of which in dicates the distance between the scraper blades.

What I claim is:

1. Apparatus for excavating soil from between vertical cylindrical concrete elements previously cast in subsoil when constructing impermeable subterranean concrete partition walls comprising an excavating tool having a central chisel, lateral half-moon-shaped blades the convex side of which faces the chisel and which have upper and lower cutting edges arranged in such a way as to widen the excavation produced by the central chisel and at the same time to scrape the two cylindrical concrete elements bordering on the excavation, and means for feeding a thixotropic substance into the excavation made by said excavating tool.

2. Apparatus as claimed in claim 1 in which the lateral half-moon blades of the excavation tool are fixed.

3. Apparatus as claimed in claim 1 including means for adjusting the lateral position of the half-moon-blades relative to each other and to said chisel.

4. Apparatus as claimed in claim 3 in which the adjustability of the mutual distance between the half-moon blades is achieved by means of a piston responsive to fluid pressure which is displaceable in a cylinder situated in a head portion of the tool above the central chisel, the blades being pivotally connected to an extension element of the piston, each by means of a pair of connecting rods parallel with one another and pivotally connected to the blades and to the extension element, another pair of connecting rods, likewise parallel, connecting each blade to a part of the tool integral with the cylinder in such a way as to form on each side of the chisel a deformable hinged parallelogram with one side adjustable in proportion to the mutual distance to be established between the two blades.

5. Apparatus as claimed in claim 4 in which the extension element of the piston to which are pivotally connected the connecting rods connected at their other ends to the scraper blades is constituted by two adjacent plates linked to the piston by means of an articulated joint.

6. Apparatus as claimed in claim 5 in which the scrap er blades are also linked to a part of the excavator tool integral with the cylinder by means of connecting rods pivotally connected to the blades and to the said part.

7. Apparatus as claimed in claim 6 including a unit for controlling the distribution of the fluid in the cylinder which actuates the movements of spacing apart or bringing together the two scraping blades, the said unit being provided with regulating means.

8. Apparatus as claimed in claim 7 in which the unit for controlling and regulating the distribution of the fluid in the cylinder which actuates the scraper blades movement comprises in addition to a powered pump and a distributor device with associated operating lever two pressure gauges made to communicate respectively with two chambers at opposite ends of the piston of the working cylinder, and a second cylinder equal to the first working cylinder and communicating therewith, the piston of which is provided externally with an index cooperating with a scale the graduation of which indicates the distance between the blades.

9. A method for the formation in sub-soil of impermeable partition walls constituted by a series of vertical mutually engaging concrete elements cast in situ, comprising the steps of casting in individual cylindrical excavations made in the subsoil along a predetermined line of any desired shape and at a substantial distance between each other, greater than the diameter of the cylindrical excavations, a series of vertically elongated cylindrical concrete elements, excavating the soil between two consecutive cylindrical elements between and up to the mutually facing convex surfaces of said two consecutive cylindrical elements, and at the same time scraping the soil from the mutually facing convex surfaces of said two cylindrical elements, to form an excavation having as the walls thereof the mutually facing convex surfaces of two adjacent cylindrical elements joined by substantially straight walls, said straight walls being parallel to each other and tangents common to both said adjacent cylindrical elements, and simultaneously as the excavation proceeds replacing the excavated material by a thixotropic fluid, and thereafter filling the excavation with concrete and repeating the same steps between each of said elements and the following one, to form link sections between the vertical cylindrical elements previously cast in the sub-soil.

10. A method for the formation in sub-soil of impermeable partition walls constituted by a series of vertical, mutually engaging, concrete elements cast in situ, comprising the steps of casting in individual excavations made in the subsoil along a predetermined line of any desired shape, a series of vertical, generally cylindrical concrete elements, said cylindrical concrete elements being at a substantial distance between each other greater than the diameter of the cylindrical elements, performing a first excavation of the soil between two consecutive cylindrical elements to form an excavation having as the sides thereof mutually opposing convex surfaces generally parallel to the mutually opposing convex surfaces of said cylindrical elements joined by substantially straight walls, each straight wall thereof lying in a plane generally par allel to a plane tangent to both cylindrical elements, respectively, said first excavation having a cross-sectional area smaller than the cross-sectional area defined by the mutually facing convex surfaces of said cylindrical elements joined by straight walls lying in planes commonly tangent to said cylindrical elements, respectively, performing a further excavation bound by the area just defined including scraping the mutually facing convex surfaces of said cylindrical elements, and as each excavation proceeds simultaneously replacing the excavated material with a thixotropic fluid to consolidate the walls of the excavation, thereafter displacing the thixotropic fluid from the excavation thus formed With concrete, and repeating the same steps between each of said elements and the following one to form link sections between the vertical elements previously cast in the sub-soil.

References Cited in the file of this patent UNITED STATES PATENTS 567,969 Eurich et al Sept. 22, 1896 814,240 Smith Mar. 6, 1906 828,189 Burpee Aug. 7, 1906 1,609,812 Goldsborough Dec. 7, 1926 2,791,886 Veder May 14, 1957 2,879,648 Wilcox Mar. 31, 1959 

1. APPARATUS FOR EXCAVATING SOIL FROM BETWEEN VERTICAL CYLINDRICAL CONCRETE ELEMENTS PREVIOUSLY CAST IN SUBSOIL WHEN CONSTRUCTING IMPERMEABLE SUBTERRANEAN CONCRETE PARTITION WALLS COMPRISING AN EXCAVATING TOOL HAVING A CENTRAL CHISEL, LATERAL HALF-MOON-SHAPED BLADES THE CONVEX SIDE OF WHICH FACES THE CHISEL AND WHICH HAVE UPPER AND LOWER CUTTING EDGES ARRANGED IN SUCH A WAY AS TO WIDEN THE EXCAVATION PRODUCED BY THE CENTRAL CHISEL AND AT THE SAME TIME TO SCRAPE THE TWO CYLINDRICAL CONCRETE ELEMENTS BORDERING ON THE EXCAVATION, AND MEANS FOR FEEDING A THIXOTROPIC SUBSTANCE INTO THE EXCAVATION MADE BY SAID EXCAVATING TOOL. 